We will continue research in respiratory mechanics in four projects: Micromechanics of the lung. Mathematical simulation of subacinar mechanics will be used to examine the magnitude of distortion by surface forces and the conditions for alveolar stability. A servo-controlled catheter will be used to study regional effective compliance and in conjunction with the mass spectrometer, collateral gas transfer. Airway aerodynamics. Work on the effects of frictional loss on flow limitation will be written up. Chest oscillation experiments by means of a new modified hydraulic chest squeezing device will be carried. out. Chest wall mechanics and respiratory control. Spinal flexion sensed with a multiple-hinge transducer will be tested as an additional degree(s) of freedom for chest wall volume change. The neural responses to change in operating length of the diaphragm will be studied in rabbits before and after cervicaldorsal root section. Development and evaluation of tests of pulmonary function. The mechanisms underlying the repeatable detail (multiple "bumps") of MEFV curves will be investigated with further studies of the influence of body posture. The newly developed methods of interrupted force oscillation and of magnetometrically anchored partial flow volume curves will be compared to standard methods for assessing airway reactivity in human subjects.